Elastin is a major protein component of connective tissue and is primarily responsible for the elasticity inherent in the aortae and large arteries. The goal of this proposal is to study the structure, biosynthesis, and assembly of elastin in aortic tissue, organ and cell cultures and in a cell-free translation assay. Crosslinked peptides and soluble elastin will be isolated from lathyritic chick aortae for both primary sequence and conformational studies. Enzymes involved in the cleavage of soluble elastin will also be studied. In order to determine the primary precursor to elastin, aortic elastin mRNA will be isolated and translated using a nuclease treated rabbit reticulocyte lysate. DNA complimentary to the elastin mRNA will be synthesized and used as quantitative probe for elastin mRNA in organ and cell cultures. Idenification of soluble elastin in the translation assay and cell and organ culture will involve SDS slab gel electrophoresis, various immunochemical techniques, peptide mapping and where possible, amino acid analysis. Smooth muscle cell cultures will be established from porcine aortic tissue for studies of elastin synthesis, and insolubilization which will be correlated with levels of elastin mRNA. The effect of lathyrogens and degraded elastin on the synthesis of elastin will also be studied. In addition, sera from lathyritic and copper-deficient chicks will be examined for the presence of antibody to soluble elastin.